1. Field of the Invention
The present invention relates to a silver halide photographic light-sensitive material and, more particularly, to a silver halide photographic light-sensitive material in which photographic useful agents, which are hard to solve in water, are added to hydrophilic organic colloid layers by dispersion using alkylamides, alkylesters, or arylesters of diphenic acid (biphenyl-2,2'-dicarboxylic acid).
2. Description of the Related Art
Conventionally, photographic useful reagents {e.g., oil-soluble couplers, antioxidants (e.g., alkylhydroquinones, alkylphenols, chromans, and coumarones) for use in preventing discoloration, color fog, or color mixing, film hardeners, oil-soluble filter dyes, oil-soluble ultraviolet absorbents, oil-soluble fluorescent brighteners, DIR compounds (e.g., DIR hydroquinones and colorless DIR couplers), developing agents, dye developing agents, DDR redox compounds, and DDR couplers} are dissolved in appropriate oil-forming agents, i.e., high boiling point organic solvents, and added to hydrophilic organic colloid layers (e.g., light-sensitive emulsion layers, filter layers, back layers, antihalation layers, interlayers, and protective layers) while being dispersed in a solution of hydrophilic organic colloid, particularly gelatin in the presence of surfactants. General examples of the high boiling point organic solvent are a phthalic acid ester compound and a phosphoric acid ester compound.
The phthalic acid ester compound or the phosphoric acid ester compound as the high boiling point organic solvent has been widely used since the compound is excellent in affinity in a colloid layer such as a gelatin layer, in effects on stability and hue of a color dye image, and in chemical stability in a light-sensitive material, and is available at a low cost.
These well-known high boiling point organic solvents (e.g., the phthalic acid ester compound and the phosphoric acid ester compounds), however, are still unsatisfactory in an effect of preventing discoloration and stains of a color dye image, caused by light, heat, or humidity, for use in recent light-sensitive materials required to have high performance.
As described above, various requirements are imposed on high boiling point organic solvents to be used in recent light-sensitive materials. For example, a high boiling point organic solvent is required to be easily obtained or manufactured at a low cost, be excellent in solubility and dispersion stability in a photographic useful reagent, and have no influence on developing and photographic properties. In addition, a high boiling point organic solvent is required to be superior in safety and have no influence on environments, and be excellent in an effect of preventing discoloration of a dye image and in chemical stability.
Recently, development has been improved in terms of rapidity, ease, and a decreased replenisher amount (including washing water) and performed in a decentralized manner rather than a centralized one. Accordingly, a problem of reduction discoloration at the time of bleaching or bleach-fixing of a cyan dye has become of major interest. It is assumed that this problem is caused because when a developing agent is carried over to a bleaching or bleach-fixing bath, an iron (III) ion complex in the bleaching or bleach-fixing bath is reduced to an iron (II) ion complex, or an iron (II) ion complex increased by fatigue in the bleaching or bleach-fixing bath reduces a cyan dye to a colorless leuco dye. Therefore, in addition to the various requirements described above, a high boiling point organic solvent is required to have an effect of suppressing reduction discoloration of a cyan dye. JP-A-62-134642 ("JP-A" means Unexamined Published Japanese Patent Application) discloses, e.g., phthalic acid ester having a bulky substituent at its ortho position, and European Patent (EP) 228,064A2 discloses, e.g., phthalic acid ester of tertiary alcohol. Each patent states an effect of suppressing reduction discoloration of a cyan dye caused by iron (II) ions and an effect of preventing discoloration and stains in a dye image caused by light, heat, or humidity.
The compounds described in these patents have an effect of preventing discoloration and stains in a dye image caused by light, heat, or humidity. However, they deteriorate the color forming properties of couplers or have no satisfactory effect of suppressing reduction discoloration of a cyan dye caused by iron (II) ions.
Recent photographic light-sensitive materials are required to have higher sensitivity, higher image quality, and higher storage stability of a color image more eagerly than before.
A strong demand, therefore, has arisen for development of a high boiling point organic solvent which does not deteriorate the color forming properties of couplers, has high storage stability of a color image, and is excellent in an effect of suppressing reduction discoloration of a cyan dye caused by iron (II) ions.
It is, however, difficult for conventional high boiling point organic solvents, including those in the two above-mentioned patents, to satisfy all these requirements.
Conventionally, benzyl alcohol has been used as a color booster in color developers for silver halide photographic light-sensitive materials. However, taking into account a recent tendency of environmental protection, color developers not essentially containing benzyl alcohol have become mainly used in order to reduce an environmental pollution load of waste liquors.